Question

考虑一个numpy数组

arr = numpy.array([[1,0,1,0,1,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,1,1,1,1,1,1,1,1],
[1,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1],
[0,0,0,0,0,1,0,1,1,1,1,1,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0]])

我希望将所有零转换为1之间的零

输出应该是

[[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],
 [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],
 [0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0]]

我怎样才能做到这一点？是否有任何numpy功能来实现这一目标？

Answer 1

这是一种使用np.maximum.accumulate的方法，通过在列翻转版本上使用它而没有它并简单地获取它们的交集 -

def fill_gaps(arr):
    ma = np.maximum.accumulate
    return ma(arr[:,::-1],axis=1)[:,::-1] & ma(arr,axis=1)

样品运行 -

# Sample #1
In [27]: print arr
[[1 0 1 0 1 0 1 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 1 1 1 1 1 1 1 1]
 [1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1]
 [0 0 0 0 0 1 0 1 1 1 1 1 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0]]

In [28]: print fill_gaps(arr)
[[1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1]
 [1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1]
 [0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0]]

# Sample #2
In [42]: print arr
[[1 0 1 0 1 0 1 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 1 1 1 1 1 1 1 1]
 [0 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 0]
 [0 0 0 0 0 1 0 1 1 1 1 1 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0]]

In [43]: print fill_gaps(arr)
[[1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1]
 [0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0]
 [0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0]]

要填充0s的数组以及其他一些值255s的数组，这里有一个修改 -

def fill_gaps(arr, value=1):
    ma = np.maximum.accumulate
    mask = arr==value
    mask_filled = ma(mask[:,::-1],axis=1)[:,::-1] & ma(mask,axis=1)
    return np.where(mask_filled,value,0)

示例运行 -

In [69]: print arr
[[255   0 255   0 255   0 255   0   0   0   0 255   0   0   0   0   0   0
    0 255   0   0 255 255 255 255 255 255 255 255]
 [  0   0   0 255   0 255   0 255   0 255   0 255   0 255   0 255   0 255
    0 255   0 255   0 255   0 255   0 255   0   0]
 [  0   0   0   0   0 255   0 255 255 255 255 255   0   0   0 255 255 255
    0   0   0   0   0   0   0   0   0   0   0   0]]

In [70]: print fill_gaps(arr, 255)
[[255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
  255 255 255 255 255 255 255 255 255 255 255 255]
 [  0   0   0 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
  255 255 255 255 255 255 255 255 255 255   0   0]
 [  0   0   0   0   0 255 255 255 255 255 255 255 255 255 255 255 255 255
    0   0   0   0   0   0   0   0   0   0   0   0]]

将所有零转换为numpy数组中的0之间的零

1 个答案: